This section is intended to provide a background or context to the disclosed embodiments. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section.
Wireless communication systems are widely deployed to provide various types of communication content such as voice, data, and other content. These systems may be multiple-access communication systems capable of supporting communication with multiple users by sharing the available system resources (e.g., bandwidth and transmit power). Examples of such multiple-access communication systems include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, Long Term Evolution (LTE) systems (including 3GPP systems), and orthogonal frequency division multiple access (OFDMA) systems.
Generally, a wireless multiple-access communication system can simultaneously support communication for multiple wireless terminals. Each terminal, or user equipment (UE), communicates with one or more base stations through transmissions on forward and reverse links. The forward link (or downlink) refers to the communication link from the base stations to the user equipment, and the reverse link (or uplink) refers to the communication link from the user equipment to the base stations. This communication link can be established through a single-in-single-out, multiple-in-single-out or a multiple-in-multiple-out (MIMO) system.
In some wireless communication systems, such as LTE systems, a random access procedure is utilized to establish or re-establish a connection between a user equipment and a base station (or eNodeB). A random access procedure may serve a number of purposes, such as to allow access when establishing a radio link (e.g., moving from an RRC_IDLE to an RRC_CONNECTED state), to re-establish a radio link upon a radio link failure, to establish uplink synchronization for a user equipment which has lost or has not acquired uplink synchronization, to facilitate handover operations when a new synchronization with new cell needs to be established, and the like. SUMMARY
This section is intended to provide a summary of certain exemplary embodiments and is not intended to limit the scope of the disclosed embodiments.
The present disclosure relates to systems, methods, apparatuses and computer program products that facilitate contention-free and contention based random access procedures in multiple component carrier wireless communication networks. One exemplary aspect relates to a method for wireless communication that comprises receiving a request for a random access procedure at a user equipment. The user equipment can be configured to operate with a plurality of component carriers including uplink and downlink component carriers in a wireless communication network. According to this exemplary method, which can be used as part of a contention-free random access procedure by the user equipment, the request is received on a first downlink component carrier of the plurality of component carriers. The method further includes selecting an uplink component carrier from among the plurality of component carriers for transmitting a random access message based on an association between the uplink and downlink component carriers. The method also can include transmitting the random access message on the selected uplink component carrier, and receiving a response to the transmitted random access message.
In one aspect of the disclosure, the selected uplink component carrier is associated with the first downlink component carrier in accordance with system information block 2 (SIB2) signaling. In another aspect, the selected uplink component carrier is associated with the first downlink component carrier in accordance with a user-equipment-specific signaling that links the first selected uplink component carrier to the selected uplink component carrier. The plurality of the component carriers may include a primary component carrier and one or more secondary component carriers, and the selected uplink component carrier can be the primary uplink component carrier.
In one aspect, the plurality of the component carriers includes a primary uplink component carrier and one or more secondary uplink component carriers, and the first downlink component carrier is associated with the primary uplink component carrier. In another aspect, the plurality of the component carriers includes a primary uplink component carrier and one or more secondary uplink component carriers, and the selected uplink component carrier is a secondary uplink component carrier. The user equipment can select a secondary uplink component carrier with an uplink timing advance value that is substantially the same as the uplink timing advance value associated with the primary uplink component carrier. In another example, the user equipment can select a secondary uplink component carrier with a different uplink timing advance value than the uplink timing advance value of the primary uplink component carrier acquire uplink synchronization for the primary uplink component carrier to enable proper transmissions of uplink control information.
According to one aspect, the request that is received at the user equipment includes information relating to the association between the first downlink component carrier and an indicated uplink component carrier, and the indicated uplink component carrier is selected as the uplink component carrier. In one example, the response to the transmitted random access message is received on a second downlink component carrier that is linked to the indicated uplink component carrier in accordance with system information block 2 (SIB2) signaling. In another example, the response to the transmitted random access message is received on the first downlink component carrier. In yet another example, the received response is a scrambled response, and the user equipment descrambles the response according to a special signature sequence number or a reserved random access radio network temporary identifier (RA-RNTI) to ascertain a particular uplink component carrier.
Another aspect relates to a method for wireless communication which includes configuring a plurality of component carriers for use by a user equipment in a wireless communication network. The plurality of component carriers may include uplink and downlink component carriers. This method may be used as part of a contention-free random access procedure by an eNodeB of the wireless communication network where each uplink component carrier is associated with at least one downlink component carrier. The method further includes selecting a downlink component carrier and transmitting a request for a random access procedure to the user equipment on the selected downlink component carrier, receiving a random access message from the user equipment on an uplink component carrier of the plurality of component carriers, where the uplink component carrier is identified by the user equipment, and transmitting a response to the user equipment.
In another aspect, the plurality of the component carriers includes a primary component carrier and one or more secondary component carriers, the selected downlink component carrier is the primary downlink component carrier, and the random access message is received on the primary uplink component carrier.
Another aspect relates to a user equipment that comprises a processor, and a memory that stores processor-executable code. The processor executable code, when executed by the processor, configures the user equipment to receive a request for a random access procedure when the user equipment is configured to operate with a plurality of component carriers which includes uplink and downlink component carriers of a wireless communication network. The request can be received on a first downlink component carrier of the plurality of component carriers. The processor executable code may also configure the user equipment to select an uplink component carrier from among the plurality of component carriers for transmitting a random access message based on an association between the uplink and downlink component carriers, transmit the random access message on the selected uplink component carrier, and receive a response to the transmitted random access message.
Another aspect relates to a device that comprises a processor and a memory that stores processor-executable code. The processor executable code, when executed by the processor, causes the device to configure a plurality of component carriers for use by a user equipment in a wireless communication network. The plurality of component carriers may include uplink and downlink component carriers for which each uplink component carrier is associated with at least one downlink component carrier. The processor executable code, when executed by the processor, configures the device to select a downlink component carrier and transmit a request for a random access procedure to the user equipment on the selected downlink component carrier. The processor executable code, when executed by the processor, enables the device to receive a random access message from the user equipment on an uplink component carrier of the plurality of component carriers, where the uplink component carrier is identified by the user equipment, and to transmit a response to the user equipment.
Another aspect relates to a device that includes means for receiving a request for a random access procedure at a user equipment, where the user equipment is configured to operate with a plurality of component carriers comprising uplink and downlink component carriers of a wireless communication network, and where the request is received on a first downlink component carrier of the plurality of component carriers. The device also includes means for selecting an uplink component carrier for transmitting a random access message based on an association between the uplink and downlink component carriers. The device also includes means for transmitting the random access message on the selected uplink component carrier, and means for receiving a response to the transmitted random access message.
Another aspect relates to a device that includes means configuring a plurality of component carriers for use by a user equipment in a wireless communication network, where the plurality of component carriers include uplink and downlink component carriers and where each uplink component carrier is associated with at least one downlink component carrier. The device also includes means for selecting a downlink component carrier and means for transmitting a request for a random access procedure to the user equipment on the selected downlink component carrier. The device can include means for receiving a random access message from the user equipment on an uplink component carrier of the plurality of component carriers, where the uplink component carrier is identified by the user equipment, and also means for transmitting a response to the user equipment.
Another aspect relates to a computer program product, embodied on a non-transitory computer-readable medium, that includes program code for receiving a request for a random access procedure at a user equipment, where the user equipment is configured to operate with a plurality of component carriers including uplink and downlink component carriers of a wireless communication network, and where the request is received on a first downlink component carrier of the plurality of component carriers. The computer program product also includes program code for selecting an uplink component carrier from among the plurality of component carriers for transmitting a random access message based on an association between the uplink and downlink component carriers, and program code for transmitting the random access message on the selected uplink component carrier. The computer program product further includes program code for receiving a response to the transmitted random access message.
Another aspect relates to a computer program product, embodied on a non-transitory computer-readable medium, that includes program code for configuring a plurality of component carriers for use by a user equipment in a wireless communication network, where the plurality of component carriers comprise uplink and downlink component carriers and where each uplink component carrier is associated with at least one downlink component carrier. The computer program product also includes program code for selecting a downlink component carrier and program code for transmitting a request for a random access procedure to the user equipment on the selected downlink component carrier. The computer program product further includes program code for receiving a random access message from the user equipment on an uplink component carrier of the plurality of component carriers, where the uplink component carrier is identified by the user equipment, and program code for transmitting a response to the user equipment.
Another aspect relates to a method for wireless communication that includes selecting an uplink component carrier for transmitting a random access request by a user equipment in a wireless communication network, where the user equipment is configured to operate with a plurality of component carriers comprising uplink and downlink component carriers. The method, which can be used as part of contention-based random access procedure by a user equipment, further includes transmitting the random access request on the selected uplink component carrier, and receiving a response to the random access request on a first downlink component carrier in the plurality of component carriers, where the first downlink component carrier is linked with the selected uplink component carrier.
In one aspect, the user equipment is configured to use a random access channel on the selected uplink component carrier. In another aspect, as part of selecting the uplink component carrier, the user equipment identifies the first downlink component carrier from an active subset of the plurality of component carriers configured for use by the user equipment. The first downlink component carrier can be linked to the selected uplink component carrier in accordance with system information block 2 (SIB2) signaling or, the first downlink component carrier can be linked to the selected uplink component carrier in accordance with a user-equipment-specific signaling. In the scenario where a user-equipment-specific signaling is used, user equipment can identify the first downlink component carrier in accordance with a random access channel (RACH) resources selected from a group including: a time resource, a frequency resource, and a signature space resource.
According to one aspect, the plurality of the component carriers can include a primary component carrier and one or more secondary component carriers, the selected uplink component carrier is the primary uplink component carrier, and the first downlink component carrier is the primary downlink component carrier. In another embodiment, the plurality of the component carriers include a primary component carrier and one or more secondary component carriers, the selected uplink component carrier is the primary uplink component carrier, and the first downlink component carrier is a secondary downlink component carrier.
In another aspect, the plurality of the component carriers can include a primary component carrier and one or more secondary component carriers, and the user equipment selects a secondary uplink component carrier with substantially the same uplink timing advance value as the primary uplink component carrier. In the scenario where the first downlink component carrier is a secondary downlink component carrier, the user equipment can acquire uplink synchronization for each secondary uplink component carriers within an active subset of the plurality of component carriers configured for use by the user equipment when the uplink timing advance value associated with each secondary uplink component carrier is different from the uplink timing advance value associated with the primary uplink component carrier. The user equipment can also acquire uplink synchronization for a one or more secondary uplink component carriers within the active subset when the uplink timing advance value associated with the one or more secondary uplink component carriers is different from the uplink timing advance value associated with the primary uplink component carrier, where the one or more secondary uplink component carriers are identified by an entity in the wireless network other than the user equipment.
In another aspect, the plurality of the component carriers can include a primary component carrier and one or more secondary component carriers, where the selected uplink component carrier is the primary uplink component carrier and the first downlink carrier is determined to be unreliable. The user equipment newly selects a secondary uplink component carrier with substantially the same uplink timing advance value as the primary uplink component carrier for the transmission of the random access request. The plurality of the component carriers can include a primary component carrier and one or more secondary component carriers, the selected uplink component carrier is the primary uplink component carrier, the first downlink carrier is determined to be unreliable, and a new primary uplink component carrier, associated with a reliable downlink component carrier, is configured for the user equipment.
According to another aspect, the plurality of component carriers can include a primary component carrier and one or more secondary component carriers, the selected uplink component carrier can be the primary uplink component carrier, the first downlink carrier is determined to be unreliable, and the user equipment receives a contention-free random access request on a reliable downlink component carrier. The request can include an indication as to an association between the primary uplink component carrier and the reliable downlink component carrier. In one aspect, the plurality of the component carriers includes a primary component carrier and one or more secondary component carriers, the selected uplink component carrier is the primary uplink component carrier, and the user equipment declares a radio link failure when the primary uplink component carrier is determined to be unreliable.
In another aspect, the plurality of the component carriers includes a primary component carrier and one or more secondary component carriers, and the user equipment selects a secondary uplink component carrier for transmitting the random access request. The selected uplink component carrier can be detected as being unreliable, the first downlink component carrier can be detected as being reliable, and the user equipment can acquire uplink synchronization for an uplink component carrier that is linked to the first downlink component carrier. In another exemplary example, the selected uplink component carrier can be detected as being unreliable, the first downlink component carrier can be detected as being reliable, and the user equipment can iteratively attempt to acquire uplink synchronization acquisition for each uplink component carrier within an active subset of the plurality of component carriers until uplink synchronization for at least one uplink component carrier is successfully attained. The user equipment can declare or provide a radio link failure if none of the synchronization acquisition attempts are successful.
Another aspect relates to a method for wireless communication that includes configuring a plurality of component carriers for use by a user equipment in a wireless communication network, where the plurality of component carriers includes uplink and downlink component carriers and where each uplink component carrier is associated with at least one downlink component carrier. This exemplary method, which can be used as part of a contention-based random access procedure by an eNodeB, further includes receiving a random access request from the user equipment on a first uplink component carrier of the plurality of component carriers, where the first uplink component carrier is identified by the user equipment. The method also includes transmitting a response on a first downlink component carrier of the plurality of component carriers, where the first downlink component carrier is linked to the first uplink component carrier.
Another aspect relates to a user equipment that comprises a processor and a memory that stores processor-executable code. The processor executable code, when executed by the processor, configures the user equipment to select an uplink component carrier for transmitting a random access request where the user equipment is configured to operate with a plurality of component carriers comprising uplink and downlink component carriers. The processor executable code, when executed by the processor, also configures the user equipment to transmit the random access request on the selected uplink component carrier, and to receive a response to the random access request on a first downlink component carrier in the plurality of component carriers, where the first downlink component carrier is linked with the selected uplink component carrier.
In one aspect, the processor executable code, when executed by the processor, configures the user equipment to acquire uplink synchronization for each secondary uplink component carriers within an active subset of the plurality of component carriers configured for use by the user equipment when the uplink timing advance value associated with each secondary uplink component carrier is different from the uplink timing advance value associated with the primary uplink component carrier. In another aspect, the processor executable code, when executed by the processor, configures the user equipment to acquire uplink synchronization for a one or more secondary uplink component carriers within an active subset of the plurality of component carriers configured for use by the user equipment when the uplink timing advance value associated with of the one or more secondary uplink component carriers is different from the uplink timing advance value associated with the primary uplink component carrier, where the one or more secondary uplink component carriers are identified by an entity in the wireless network other than the user equipment.
Another aspect relates to a user equipment that comprises a processor and a memory that stores processor-executable code. The processor executable code, when executed by the processor, configures a user equipment to utilize a plurality of component carriers, where the plurality of component carriers includes uplink and downlink component carriers and where each uplink component carrier is associated with at least one downlink component carrier. The processor executable code, when executed by the processor, also configures the user equipment to receive a random access request on a first uplink component carrier of the plurality of component carriers, where the first uplink component carrier is identified by the user equipment. The processor executable code, when executed by the processor, additionally configures the user equipment to transmit a response on a first downlink component carrier of the plurality of component carriers, where the first downlink component carrier is linked to the first uplink component carrier.
Another aspect relates to a wireless communication device that includes means for selecting an uplink component carrier for transmitting a random access request by a user equipment, where the user equipment is configured to operate with a plurality of component carriers comprising uplink and downlink component carriers. The wireless communication device also includes means for transmitting the random access request on the selected uplink component carrier, and means for receiving a response to the random access request on a first downlink component carrier in the plurality of component carriers, where the first downlink component carrier is linked with the selected uplink component carrier.
Another aspect relates to a wireless communication device that includes means for configuring a plurality of component carriers for use by a user equipment in a wireless communication network, where the plurality of component carriers comprise uplink and downlink component carriers and where each uplink component carrier is associated with at least one downlink component carrier. The wireless communication device also includes means for receiving a random access request from the user equipment on a first uplink component carrier of the plurality of component carriers, where the first uplink component carrier is identified by the user equipment. The wireless communication device further includes means for transmitting a response on a first downlink component carrier of the plurality of component carriers, where the first downlink component carrier is linked to the first uplink component carrier.
Another aspect relates to a computer program product, embodied on a non-transitory computer-readable medium that includes program code for selecting an uplink component carrier for transmitting a random access request by a user equipment in a wireless communication network, where the user equipment is configured to operate with a plurality of component carriers comprising uplink and downlink component carriers. The computer program product further includes program code for transmitting the random access request on the selected uplink component carrier, and program code for receiving a response to the random access request on a first downlink component carrier in the plurality of component carriers, where the first downlink component carrier is linked with the selected uplink component carrier.
Another aspect relates to a computer program product, embodied on a non-transitory computer-readable medium that includes program code for configuring a plurality of component carriers for use by a user equipment in a wireless communication network, where the plurality of component carriers includes uplink and downlink component carriers and where each uplink component carrier is associated with at least one downlink component carrier. The computer program product further includes program code for receiving a random access request from the user equipment on a first uplink component carrier of the plurality of component carriers, where the first uplink component carrier is identified by the user equipment. The computer program product additionally includes program code for transmitting a response on a first downlink component carrier of the plurality of component carriers, wherein the first downlink component carrier is linked to the first uplink component carrier.
These and other features of various embodiments, together with the organization and manner of operation thereof, will become apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which like reference numerals are used to refer to like parts throughout.